Veritas Backup Exec Remote Agent NDMLSRVR.DLL DoS Vulnerability iDEFENSE Security Advisory 06.23.05 www.idefense.com/application/poi/display?id=270&type=vulnerabilities June 23, 2005 I. BACKGROUND VERITAS Backup Exec is an advanced backup and restore solution for Microsoft Windows server environments. More information is available from the vendor's website: http://veritas.com/Products/www?c=product&refId=57 II. DESCRIPTION Remote exploitation of a denial of service condition in Veritas Software Corp.'s Backup Exec allows attackers to crash the vulnerable service. The Veritas Backup Exec Agent listens on TCP port 10000 and is responsible for accepting connections from the backup server when a backup is to occur. Typically the agent would be installed on most servers and important workstations in an enterprise environment. Veritas Backup Exec uses the standard NMDP protocol to communicate with the listening agents. The vulnerability specifically exists within NDMLSRVR.DLL due to a null pointer dereference upon parsing of a maliciously crafted packet at the following instruction: 0x01053355 MOVZX EAX, WORD PTR [ESI] An unhandled exception occurs resulting in a crash of the program and a denial of service condition. III. ANALYSIS Exploitation does not require authentication, thereby allowing any remote attacker to cause the denial of service and disruption of backup capabilities. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in Backup Exec for Windows Servers version 10.0 and 10.0 SP1, the latest versions available as of this report. It is suspected that older versions are also vulnerable. Several vendors ship or use Veritas software including Hitachi and NEC Corporation. V. WORKAROUND Use a firewall to restrict incoming connections to trusted workstations running the Backup Exec client software which uses port 10000 TCP. VI. VENDOR RESPONSE The vendor has addressed this vulnerability in security advisory VX05-001: http://seer.support.veritas.com/docs/276533.htm VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2005-0772 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. VIII. DISCLOSURE TIMELINE 05/13/2005 Initial vendor notification 05/13/2005 Initial vendor response 06/22/2005 Coordinated public disclosure IX. CREDIT Sebastian Apelt is credited with this discovery. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp Free tools, research and upcoming events http://labs.idefense.com X. LEGAL NOTICES Copyright (c) 2005 iDEFENSE, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDEFENSE. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information. _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/